American children are back in school, but homework isn’t all they’re bringing home — they’re likely bringing home thousands of microscopic germs. NSF International, an independent, not-for-profit organization, recently collected and tested samples and found as many as 2.7 million bacterial cells per square inch on common school surfaces such as water fountains, desks, computer keyboards, bus seats and cafeteria trays.

"We collected samples from many different commonly used surfaces in a typical elementary school," says Rob Donofrio, director of the microbiology and molecular biology for NSF. "What we found was that surfaces where one would expect the most germs and bacteria, such as toilets and door handles, actually have fewer germs because they are cleaned and disinfected most often. Other surfaces such as drinking water fountains and headphones, are often overlooked and, as a result, have even more microorganisms."

NSF’s startling findings include:

  • Drinking water fountain spigots had the highest amount of bacteria on the tested surfaces.
  • A cafeteria tray had more than ten times as many germs as a toilet seat.
  • A student’s hand had 1,500 bacterial cells per square inch.
  • Commonly cleaned areas, such as desks and doorknobs had fewer germs while computer keyboards and ear phones had significantly more at 260 bacterial cells per square inch and 740 bacterial cells per square inch respectively.